U.S. patent number 4,769,831 [Application Number 06/912,276] was granted by the patent office on 1988-09-06 for rotating anode x-ray tube.
This patent grant is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Karlheinz Broenner.
United States Patent |
4,769,831 |
Broenner |
September 6, 1988 |
Rotating anode x-ray tube
Abstract
A rotating anode x-ray tube has an anode magnetically seated in
a housing in non-contacting fashion. For non-contacting
transmission and dissipation of the anode current, a hollow
cylindrical rotor of the anode is provided with ribs on its
interior surface. A stationary hollow cylinder is disposed inside
of the rotor, the stationary hollow cylinder being also provided
with ribs in registry with the ribs on the interior of the rotor,
and being connected to the anode lead. Current is thereby
transferred from the stationary cylinder to the rotating hollow
cylinder by corona discharge.
Inventors: |
Broenner; Karlheinz (Erlangen,
DE) |
Assignee: |
Siemens Aktiengesellschaft
(Berlin and Munich, DE)
|
Family
ID: |
6285916 |
Appl.
No.: |
06/912,276 |
Filed: |
September 29, 1986 |
Foreign Application Priority Data
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Nov 13, 1985 [DE] |
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3540303 |
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Current U.S.
Class: |
378/125;
378/144 |
Current CPC
Class: |
H01J
35/103 (20130101) |
Current International
Class: |
H01J
35/10 (20060101); H01J 35/00 (20060101); H01J
035/26 () |
Field of
Search: |
;378/125,144,93,132
;310/308,309,232 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0126668 |
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Nov 1984 |
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EP |
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0132180 |
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Jan 1985 |
|
EP |
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Primary Examiner: Howell; Janice A.
Assistant Examiner: Porta; David P.
Attorney, Agent or Firm: Hill, Van Santen, Steadman &
Simpson
Claims
I claim as my invention:
1. In a rotating anode x-ray tube having an anode mounted an a
shaft and means for magnetically seating said anode in a housing
during rotation in a non-contacting manner, and having an anode
terminal, the improvement comprising:
a hollow rotor connected to said anode shaft, said hollow rotor
having an interior surface with ribs thereon; and
a stationary cylinder disposed inside said hollow rotor and
connected to said anode terminal, said stationary cylinder having
an exterior surface with ribs thereon corresponding to said ribs in
said interior of said rotor and disposed with respect thereto for
transferring current between said rotor and said cylinder by corona
discharge.
2. In a rotating anode x-ray tube having an anode connected to a
shaft and means for magnetically seating said anode in a housing in
a non-contacting manner and having an anode terminal, the
improvement comprising:
a first cylindrical part connected to said anode shaft for
co-rotation therewith having a surface with ribs thereon; and
a stationary cylindrical part disposed in said housing having a
surface with ribs thereon disposed spaced from and adjacent said
ribs of said co-rotating cylindrical part for transferring current
between said co-rotating part and said stationary part by corona
discharge.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to rotating anode x-ray tubes, and in
particular to such x-ray tubes wherein the anode is magnetically
seated in a housing in a non-contacting manner.
2. Description of the Prior Art
A rotating anode x-ray tube is described in German No. OS 30 43 670
wherein the shaft of the anode is magnetically seated in a housing
in a non-contacting manner. The seating of the anode shaft is
accomplished by a non-contacting magnetic bearing, which axially
and radially holds the shaft. Because the anode is maintained
suspended during operation, a problem exists in carrying away the
anode current. The solution is this problem described in German No.
OS 30 43 670 is to arrange at least one auxiliary cathode on a
component rotating together with the anode, this auxiliary cathode
having a stationary auxiliary anode allocated thereto. Dissipation
of the anode current occurs through an auxiliary diode which is
disposed at the anode side, so that direct contact between the
auxiliary anode and auxiliary cathode does not occur. As a result
of the required auxiliary cathode and auxiliary anode, however, the
outlay for this structure is high.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rotating
anode x-ray tube wherein the anode is magnetically mounted in a
housing in a non-contacting manner and wherein a means for
eliminating the anode current is provided having a reduced
structural outlay.
The above object is achieved in accordance with the principles of
the present invention in a rotating anode x-ray tube wherein the
anode has a cylindrical shaft rotating therewith which has an
exterior surface with ribs thereon. Corresponding ribs are provided
on a stationary portion of the x-ray tube housing opposite the ribs
on the cylindrical shaft. A current transfer between the rotating
shaft and the stationary part occurs by corona or brush discharge.
In the x-ray tube disclosed herein, the anode floats in a magnetic
field. The current transfer from the anode to the anode terminal
occurs by corona discharge because an adequately large surface
which is electrically connected to the anode and a surface lying
closely adjacent opposite this surface are provided. The latter
surface is fashioned such that corona discharge can easily occur
between the surface. The ribs on the rotating and stationary parts
can be fashioned in the form of a thread with a suitable coating
of, for example, tungsten.
DESCRIPTION OF THE DRAWINGS
The single FIGURE shows a side view in section of a rotating anode
x-ray tube constructed in accordance with the principles of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in the single FIGURE, an x-ray tube has a glass housing 1
in which an anode 2 rotates. The anode 2 has an anode plate or dish
3 which is secured on a shaft 4 and to which a cathode 5 is
allocated in a known manner. The cathode 5 supplies the electron
current required for generating x-radiation. The shaft 4 is
connected to a rotor 6 which rotates the anode 2 and permits
magnetic support thereof. The anode 2 is thus held magnetically
suspended during rotation. For this purpose, a stationary magnetic
winding 7 is provided surrounding a neck 8 of the glass housing 1.
A drive winding 8a is provided for rotating the anode 2.
The anode 2 has no mechanical contact whatsoever to stationary
parts while it rotates. In order for the anode current to be
transmitted away in a non-contacting manner, the rotor 6 is in the
form of a hollow cylinder having a plurality of ribs 9 on its
interior surface. A stationary cylinder 11 is provided inside the
hollow rotor 6 which has corresponding ribs 10 on an exterior
surface thereof. The stationary cylinder 11 is connected to an
anode terminal 12.
As a consequence of the large surfaces on the inside of the rotor 6
and the outside of the cylinder 11 formed by the respective sets of
ribs 9 and 10, corona or brush discharge occurs between the rotor 6
and the cylinder 11, which achieves transfer of current between
those components.
The cylinder 11 has two ball bearings 13 disposed at a distance
from the inside of the rotor 6 during rotation of the anode 2,
which support the rotor 2 during standstill.
Although modifications and changes may be suggested by those
skilled in the art it is the intention of the inventor to embody
within the patent warranted hereon all changes and modifications as
reasonably and properly come within the scope of his contribution
to the art.
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